Trimanganese tetraoxide attracts attention as a manganese material of a lithium manganese oxide due to its high fillability.
As a method for producing trimanganese tetraoxide, a method has been reported by which manganese hydroxide is formed from a manganese solution, which is oxidized to obtain trimanganese tetraoxide (for example, Patent Documents 1 and 2).
As another method for producing trimanganese tetraoxide, a method for producing trimanganese tetraoxide having a maximum particle size of at most 150 nm has been reported by which an alkali liquid is mixed with a manganese-containing liquid, followed by oxidation (for example, Patent Document 3).